This commit makes the messages of the timer feature to be proxied by
akka-apps and also adds a timer model that is updated based on these
messages.
Moving the timer panel opening logic to the timer button component in
the navigation panel was a consequence of these changes.
When user enters meeting with music already playing, an event listener is set
to play the music only after user interaction.
Also, to keep timer more cohesive and reduce complexity of the condition for
playing music, timer automatically stops after 90% of users notify that the
timer has expired.
Adds a music player for ambient sound which can be turned on and off using a
toggle located inside timer panel. When stopwatch is selected, this toggle is
automattically turned off.
